The present invention relates to a technology for reducing cost for a semiconductor data storage apparatus and, more particularly, to a technology which is effective when applied to cost reduction for a memory card using a nonvolatile memory.
As external memory media for a personal computer, a multi-function terminal, and the like, there have been widely known semiconductor data storage apparatus such as a CF (Compact Flash) card, smart media, a memory stick, and a multimedia card.
In general, a semiconductor data storage apparatus comes in various versions prepared for different purposes, which include a low-price version, a standard version, and a high-reliability/high-value-added version with an increased added value. In the low-price version, for example, an analog module including a power supply circuit, a clock generator circuit, and a power supply monitor circuit has preliminarily been mounted on a controller, thereby achieving cost reduction.
In the semiconductor data storage apparatus in the high-reliability version, on the other hand, a power supply circuit, a clock generator circuit, a power supply monitor circuit, and the like are not mounted on a controller but formed as an external analog module, thus providing a structure which further enhances reliability.
In the semiconductor data storage apparatus in the standard version, some of a power supply circuit, a clock generator circuit, a power supply monitor circuit, and the like are formed as an internal analog module which is mounted on a controller, while the others are formed as an external analog module, thereby providing a structure which offers a balance between cost and reliability.
Examples in which power supply circuits in nonvolatile semiconductor memories of this type are described in detail include one in which plural types of internal voltages are generated (Patent Document 1) and one in which trimming means for the pulse width of a write voltage is provided (Patent Document 2).
[Patent Document 1] Japanese Laid-Open Patent Publication No. Hei 07(1995)-176698 (U.S. Pat. No. 5,553,021)
[Patent Document 2] Japanese Laid-Open Patent Publication No. Hei 10(1998)-106276 (U. S. Pat. No. 6,091,640)